But, alas for Granada! war hung round its borders, and the blare of the trumpet and clash of the sword were ever familiar sounds within its confines. Christian kingdoms surrounded it, whose people envied the Moslems this final abiding-place on the soil of Spain. Hostilities were ceaseless on the borders; plundering forays were the delight of the Castilian cavaliers and the Moorish horsemen. Every town was a fortress, and on every peak stood a watch-tower, ready to give warning with a signal fire by night or a cloud of smoke by day of any movement of invasion. For many years such a state of affairs continued between Granada and its principal antagonist, the united kingdoms of Castile and Leon. Even when, in 1457, a Moorish king, disheartened by a foray into the vega itself, made a truce with Henry IV., king of Castile and Leon, and agreed to pay him an annual tribute, the right of warlike raids was kept open. It was only required that they must be conducted secretly, without sound of trumpet or show of banners, and must not continue more than three days. Such a state of affairs was desired alike by the Castilian and Moorish chivalry, who loved these displays of daring and gallantry, and enjoyed nothing more than a crossing of swords with their foes. In 1465 a Moorish prince, Muley Abul Hassan, a man who enjoyed war and hated the Christians, came to the throne, and at once the tribute ceased to be paid. For some years still the truce continued, for Ferdinand and Isabella, the new monarchs of Spain, had troubles at home to keep them engaged. But in 1481 the war reopened with more than its old fury, and was continued until Granada fell in 1492, the year in which the wise Isabella gave aid to Columbus for the discovery of an unknown world beyond the seas. The war for the conquest of Granada was one full of stirring adventure and hair-breadth escapes, of forays and sieges, of the clash of swords and the brandishing of spears. It was no longer fought by Spain on the principle of the raid,—to dash in, kill, plunder, and speed away with clatter of hoofs and rattle of spurs. It was Ferdinand’s policy to take and hold, capturing stronghold after stronghold until all Granada was his. In a memorable pun on the name of Granada, which signifies a pomegranate, he said, "I will pick out the seeds of this pomegranate one by one." Muley Abul Hassan, the new Moorish king, began the work, foolishly breaking the truce which Ferdinand wished a pretext to bring to an end. On a dark night in 1481 he fell suddenly on Zahara, a mountain town on the Christian frontier, so strong in itself that it was carelessly guarded. It was taken by surprise, its inhabitants were carried off as slaves, and a strong Moorish garrison was left to hold it.